Structures and methods for use in photolithography

ABSTRACT

Methods of forming structures including a stress management layer for photolithography and structures including the stress management layer are disclosed. Further disclosed are systems for depositing a stress management layer. Exemplary methods include forming the stress management layer using one or more of plasma-enhanced cyclic (e.g., atomic layer) deposition and plasma-enhanced chemical vapor deposition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Ser. No. 63/053,420 filed Jul. 17, 2020 titled “STRUCTURES AND METHODS FOR USE IN PHOTOLITHOGRAPHY,” the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF INVENTION

The present disclosure generally relates to structures and to methods of forming the structures. More particularly, the disclosure relates to structures for use in photolithography and to methods of forming such structures.

BACKGROUND OF THE DISCLOSURE

During the manufacture of electronic devices, fine patterns of features can be formed on a surface of a substrate by patterning the surface of the substrate and etching material from the substrate surface using, for example, gas-phase etching processes. As a density of devices on a substrate increases, it becomes increasingly desirable to form features with smaller dimensions.

Photoresist is often used to pattern a surface of a substrate prior to etching. A pattern can be formed in the photoresist, by applying a layer of photoresist to a surface of the substrate, masking the surface of the photoresist, exposing the unmasked portions of the photoresist to radiation and removing a portion (e.g., the unmasked or masked portion) of the photoresist, while leaving a portion of the photoresist on the substrate surface. Recently, techniques have been developed to use extreme ultraviolet (EUV) wavelengths to develop patterns having relatively small pattern features (e.g., 10 nm or less). However, reliably transferring small pattern features to a wafer remains a challenge. For example, amorphous or carbon or spin-on-carbon lines having a critical dimension of 10 nm or less may become very sensitive to surface roughness features such as, e.g. wiggling, such that it can become very difficult to achieve acceptable line edge roughness and/or line width roughness. In addition, lithographic processes for defining very small pattern features can become very sensitive to wafer bowing, which further complicates such processes.

Any discussion of problems and solutions set forth in this section has been included in this disclosure solely for the purpose of providing a context for the present disclosure and should not be taken as an admission that any or all of the discussion was known at the time the invention was made.

The following prior art documents are made of record: De Silva, A.; Dutta, A.; Meli, L.; Yao, Y.; Mignot, Y.; Guo, J.; Felix, N. Inorganic Hardmask Development For Extreme Ultraviolet Patterning. Journal of Micro/Nanolithography, MEMS, and MOEMS 2018, 18, 1; Felix, N.; Singh, L.; Seshadri, I.; Silva, A.; Meli, L.; Liu, C.; Chi, C.; Guo, J.; Truang, H.; Schmidt, K. et al. Ultrathin Extreme Ultraviolet Patterning Stack Using Polymer Brush As An Adhesion Promotion Layer. Journal of Micro/Nanolithography, MEMS, and MOEMS 2017, 16, 1; Tatehaba, Y. Adhesion energy of polystyrene in function water, In 5th International Symposium of Cleaning Technology in Semiconductor Device Manufacturing; 1998; pp. 560-565; Fallica, R.; Stowers, J.; Grenville, A.; Frommhold, A.; Robinson, A.; Ekinci, Y. Dynamic Absorption Coefficients Of Chemically Amplified Resists And Nonchemically Amplified Resists At Extreme Ultraviolet. Journal of Micro/Nanolithography, MEMS, and MOEMS 2016, 15, 033506; US20180358222 describes high-density low temperature carbon films for hardmask and other patterning applications; U.S. Pat. No. 6,265,113 describes a stress adjustment method of an x-ray mask; U.S. Pat. No. 3,962,004 describes pattern definition in an organic layer; Japanese Journal of Applied Physics 53, 03DE01 (2014) describes line-edge roughness increase due to wiggling enhanced by initial pattern waviness; Japanese Journal of Applied Physics 54, 06FH04 (2015) describes a mechanism of wiggling enhancement due to HBr gas addition during amorphous carbon etching.

SUMMARY OF THE DISCLOSURE

Various embodiments of the present disclosure relate to structures including stress management layers and to methods of forming the layers and structures. While the ways in which various embodiments of the present disclosure address drawbacks of prior methods and structures are discussed in more detail below, in general, various embodiments of the disclosure provide structures that can include a relatively thin, uniform photoresist underlayer with desired properties, such as desired etch selectivity, pattern quality, and/or stability.

In particular, described herein is a method for forming a structure. The method comprises providing a substrate comprising a carbon-containing layer having a compressive stress to a reaction chamber, and providing a precursor in the reaction chamber to deposit a stress management layer on the carbon-containing layer. The stress management layer has a tensile stress.

In some embodiments, providing a precursor in the reaction chamber to depositing a stress management layer comprises providing a plasma in the reaction chamber.

In some embodiments, the precursor comprises carbon and hydrogen. In some embodiments, the ratio of the carbon concentration and the hydrogen concentration in the stress management layer is at least 0.8, when the carbon concentration and the hydrogen concentration are expressed on a per mol basis. In some embodiments, the precursor further comprises a halogen. In some embodiments, the halogen is bromine. In some embodiments, the precursor comprises tribromomethane. In some embodiments, the precursor comprises fluorine. In some embodiments, the precursor comprises C₈F₁₈. In some embodiments, the precursor further comprises oxygen and/or nitrogen. In some embodiments, the precursor further comprises phosphorous and/or boron. In some embodiments, the precursor comprises a C₁ to C₂₀ alkane, a C₁ to C₂₀ alkene, a C₁ to C₂₀ alkyl, or a C₁ to C₂₀ polyunsaturated hydrocarbon. In some embodiments, the precursor comprises CH₄. In some embodiments, the precursor comprises an aromatic compound. In some embodiments, the precursor is selected from toluene, and trimethylbenzene. In some embodiments, the precursor is an aliphatic compound. In some embodiments, the precursor comprises an organoborane. In some embodiments, the precursor comprises an alkyl boron. In some embodiments, the precursor comprises triethylboron.

In some embodiments, the stress management layer is deposited using a reactant selected from the list consisting of O₂, CO₂, N₂O, CO, a mixture of N₂ and a noble gas, a mixture of N₂ and H₂, and a mixture of NH₃ and a noble gas. In some embodiments, the noble gas comprises Ar.

In some embodiments, the precursor comprises triethylboron and the reactant comprises Ar.

In some embodiments, the stress management layer is deposited using a cyclical deposition process.

In some embodiments, the cyclical deposition process comprises cyclically providing precursor pulses and reactant pulses to the reaction chamber. The precursor pulses comprise providing the precursor to the reaction chamber, and the reactant pulses comprise providing the reactant to the reaction chamber. In some embodiments, the precursor pulses and the reactant pulses are separated by purges.

In some embodiments, the cyclical deposition process further comprises exposing the substrate to a plasma. In some embodiments, the plasma is continuous, i.e., not intermittent, or in other words, always on throughout the deposition of the stress management layer. In some embodiments, the plasma is pulsed.

In some embodiments, the stress management layer is deposited at a temperature of at least 20° C. to at most 400° C. In some embodiments, the stress management layer is deposited at a pressure of at least 1.0 Torr to at most 50.0 Torr.

In some embodiments, the stress management layer does not comprise silicon, titanium, or zinc. In some embodiments, the stress management layer consists of C, H, O, and N.

In some embodiments, the method further comprises a step of subjecting the stress management layer to a plasma treatment.

In some embodiments, the carbon-containing layer has a thickness of at least 100 nm to at most 250 nm. In some embodiments, the stress management layer has a thickness of at most 10 nm.

In some embodiments, the method further comprises a step of depositing an underlayer on the stress management layer. In some embodiments, the underlayer has a thickness of less than 5 nm. In some embodiments, the underlayer has a surface energy having a polar part and a dispersive part, wherein polar part of the surface energy is from at least 3 mN/m to at most 13 mN/m. In some embodiments, the underlayer is formed by means of a cyclical plasma-enhanced deposition process. In some embodiments, the underlayer comprises silicon, oxygen, hydrogen, and carbon. In some embodiments, the underlayer further comprises nitrogen. In some embodiments, the method further comprises a step of exposing the underlayer to a plasma, the plasma comprising one or more elements selected from the list consisting of a halogen, oxygen, hydrogen, and nitrogen. In some embodiments, the halogen is chlorine. In some embodiments, the underlayer comprises a bi-layer structure comprising an upper underlayer part and a lower underlayer part, wherein the lower underlayer part comprises a metal or metalloid.

Further described herein is a system comprising one or more reaction chambers configured for carrying out a method as described herein.

Further described herein is a method of forming a structure, the method comprising the steps of: providing a substrate; forming a carbon-containing layer overlying a surface of the substrate, the carbon-containing layer having a compressive stress; forming a stress management layer overlying a surface of the carbon-containing layer, the stress management layer having a tensile stress; forming an underlayer overlying a surface of the stress management layer; and forming a photoresist layer overlying the underlayer. The photoresist layer comprises extreme ultraviolet (EUV) lithography photoresist.

These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures; the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of exemplary embodiments of the present disclosure can be derived by referring to the detailed description and claims when considered in connection with the following illustrative figures.

FIGS. 1-6 illustrate structures formed using positive tone photoresist in accordance with at least one embodiment of the disclosure.

FIGS. 7-12 illustrate structures formed using negative tone photoresist in accordance with at least one embodiment of the disclosure.

FIG. 13 illustrates a method of forming a structure in accordance with at least one embodiment of the disclosure.

FIG. 14 illustrates a stack of layers including a stress management layer that has been deposited in accordance with to at least one embodiment of the disclosure.

FIGS. 15 and 16 illustrate a pulsing regime of a method in accordance with at least one embodiment of the disclosure.

Throughout the figures, the following numbering is adhered to: 100—structure; 102—substrate; 104—patternable layer; 106—carbon-containing layer; 108—stress management layer; 110—underlayer; 112—photoresist layer; 200—structure; 202—exposed structure; 204—unexposed structure; 300—structure; 400—structure; 402—features; 410—underlayer material; 412—photoresist material; 500—structure; 501—features; 504—patternable material; 506—carbon-containing material; 508—stress management material; 510—underlayer material; 700—structure; 702—substrate; 704—patternable layer; 706—carbon-containing layer; 708—stress management layer; 710—underlayer; 712—photoresist layer; 800—structure; 802—exposed structures; 804—unexposed structures; 900—structure; 1000—structure; 1001—features; 1004—photoresist material; 1006—underlayer material; 1100—structure; 1101—features; 1104—patternable layer material; 1106—carbon-containing layer material; 1108—stress management layer material; 1110—underlayer material; 1200—structure; 1202—structures; 1300—method; 1302—forming a carbon-containing layer; 1303—forming a stress management layer; 1304—forming an underlayer; 1306—treatment; 1308—forming a layer of photoresist; 1410—substrate; 1420—underlayer; 1421—lower underlayer part; 1422—upper underlayer part; 1501—plasma power; 1502—plasma gas flow; 1503—precursor flow; 1504—timeline; 1601—plasma power; 1602—plasma gas flow; 1603—precursor flow; 1604—timeline.

It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below.

As used herein, the term “substrate” may refer to any underlying material or materials that may be used to form, or upon which, a device, a circuit, or a film may be formed. A substrate can include a bulk material, such as silicon (e.g., single-crystal silicon), other Group IV materials, such as germanium, or compound semiconductor materials, such as GaAs, and can include one or more layers overlying or underlying the bulk material. Further, the substrate can include various features, such as recesses, lines, and the like formed within or on at least a portion of a layer of the substrate.

In some embodiments, the terms “film” and “layer” may be used interchangeably and refer to a layer extending in a direction perpendicular to a thickness direction to cover an entire target or concerned surface, or simply a layer covering a target or concerned surface. In some embodiments, the terms “film” or “layer” refer to a structure having a certain thickness formed on a surface. A film or layer may be constituted by a discrete single film or layer having certain characteristics. Alternatively, a film or layer may be constituted of multiple films or layers, and a boundary between adjacent films or layers may or may not be clear and may or may not be established based on physical, chemical, and/or any other characteristics, formation processes or sequence, and/or functions or purposes of the adjacent films or layers.

Further, in this disclosure, any two numbers of a variable can constitute a workable range of the variable, and any ranges indicated may include or exclude the endpoints. Additionally, any values of variables indicated (regardless of whether they are indicated with “about” or not) may refer to precise values or approximate values and include equivalents, and may refer to average, median, representative, majority, etc. in some embodiments. Further, in this disclosure, the terms “including,” “constituted by” and “having” refer independently to “typically or broadly comprising,” “comprising,” “consisting essentially of,” or “consisting of” in some embodiments. In this disclosure, any defined meanings do not necessarily exclude ordinary and customary meanings in some embodiments. Percentages set forth herein are absolute percentages, unless otherwise noted.

It shall be understood that the term “comprising” is open ended and does not exclude the presence of other elements or components, unless the context clearly indicates otherwise. The term “comprising” includes the meaning of “consisting of”. The term “consisting of” indicates that no other features or components are present than those mentioned, unless the context indicates otherwise.

As used herein, the term “patternable layer” refers to a layer into which a lithographically defined pattern can be transferred, e.g., by means of an etch. A “patternable layer” may be a distinct layer, or it may be part of a substrate. Exemplary patternable layers include low-k dielectrics such as porous or non-porous silicon oxycarbide layers, amorphous carbon layers, amorphous silicon layers, organic or inorganic spin-on materials, metal layers such as titanium, tungsten, ruthenium, or copper, layers, layers comprising metal alloys, and metal nitride layers such as titanium nitride layers or vanadium nitride layers, oxide layers such as silicon oxide layers, amongst others. A patternable layer may also consist of a stack of constituent layers, which may have a different structure and/or morphology. The term “patternable layer” may be used interchangeably with terms such as “layer”, “material layer”, and the like.

The term “cyclical deposition process” may refer to the sequential introduction of precursors (reactants) into a reaction chamber to deposit a layer over a substrate and includes processing techniques such as atomic layer deposition and cyclical chemical vapor deposition.

The term “atomic layer deposition” (ALD) may refer to a vapor deposition process in which deposition cycles, typically a plurality of consecutive deposition cycles, are conducted in a process chamber. Generally, during each cycle, a precursor is chemisorbed to a deposition surface (e.g., a substrate surface that can include a previously deposited material from a previous ALD cycle or other material), forming about a monolayer or sub-monolayer of material that does not readily react with additional precursor (i.e., a self-limiting reaction). Thereafter, in some cases, a co-reactant (e.g., another precursor or reaction gas) may subsequently be introduced into the process chamber for use in converting the chemisorbed precursor to the desired material on the deposition surface. The co-reactant can be capable of further reaction with the precursor. Further, purging steps can also be utilized during each cycle to remove excess precursor from the process chamber and/or remove excess co-reactant and/or reaction byproducts from the process chamber after conversion of the chemisorbed precursor. Further, the term atomic layer deposition, as used herein, is also meant to include processes designated by related terms, such as chemical vapor atomic layer deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy when performed with alternating pulses of precursor(s)/reactive gas(es), and purge (e.g., inert carrier) gas(es).

The term “cyclic chemical vapor deposition process” may refer to a chemical vapor deposition process in which one or more precursors are provided to a reaction chamber intermittently, i.e., in pulses. A plasma enhanced cyclic chemical vapor deposition process may refer to a cyclic chemical vapor deposition process in which a plasma is used to generate reactive species.

In some embodiments, the term “PEALD” may refer to cyclic deposition processes in which one or more reagents are provided in pulses, i.e. intermittently. The steps in PEALD processes may not necessarily be self-limiting. In some embodiments though, a PEALD process comprises one or more self-limiting steps. Optionally, all steps in a PEALD process are self-limiting. An example of a cyclic PECVD process includes a plasma-assisted process in which one reagent is continuously provided to a reaction chamber while another reagent is provided to the reaction chamber in a plurality of pulses. In some embodiments, a PEALD process can employ a pulsed plasma. Alternatively, a PEALD process can employed a continuously on plasma.

The present disclosure generally relates to methods of forming structures that include a stress management layer and to structures including a stress management layer. As described in more detail below, exemplary methods can be used to form structures with stress management layers that provide desired properties, such as desired thickness (e.g., less than 10 or less than 5 nm), relatively low surface roughness, good adhesion to a photoresist underlayer, desired etch selectivity, desired thickness uniformity—both within a substrate (e.g., a wafer) and between substrates, high pattern quality (low number of defects and high pattern fidelity), low line edge roughness (LER), low line width roughness (LWR), stability during EUV lithography processing—e.g., during any post-exposure bake (PEB), photoresist development, reworking of the substrate, reasonable EUV sensitivity, and compatible with integration (i.e., under the deposition condition of underlayer, other layers underneath shall not be damaged. e.g., not too high deposition temperature). The present stress management layers may further offer the possibility of being etchable by etchants which also etch resist and carbon-containing layers such as amorphous carbon, spin-on carbon (SOC), and carbon hardmasks. The present photoresist underlayers may further be used in combination with such layers, i.e., in combination with resist, underlayers, and carbon-containing layers such as spin-on carbon (SOC), carbon hardmask (CHM) or amorphous carbon (APF) layers. The present stress management layers may further resist baking steps.

Thus described herein is a method which may be used for forming a carbon-based hardmask for use in photolithographic processes, such as extreme EUV photolithography. It is particularly useful for stress management in lithographic structures. The carbon hardmask comprises a carbon containing layer and a stress management layer which may be deposited according to the methods that are described herein. The present stress management layers are easy to volatilize, e.g., in an oxygen-containing or a nitrogen-containing plasma. Therefore, they can be easily removed from a substrate after a patterning step.

Thus described is a method comprising a step of providing a substrate to a reaction chamber. The substrate may comprise a carbon-containing layer at its surface. In other words, the substrate may comprise an exposed carbon-containing layer. In case the substrate does not comprise a carbon containing layer when it is provided to the reaction chamber, then the method suitably involves a step of depositing a carbon-containing layer on the substrate. The carbon containing layer may be directly deposited on the bulk substrate in case the substrate bulk is to be patterned, or the carbon-containing layer may be deposited on a patternable layer on the substrate which may have a different composition from the bulk of the substrate. The carbon-containing layer may comprise sp3 carbon and/or sp2 carbon. The carbon-containing layer may comprise diamond-like carbon. The carbon-containing layer has a compressive stress. The carbon-containing layer may be deposited, for example, by means of a hydrocarbon-containing plasma. The method further comprises a step of providing a precursor to the reaction chamber, thus depositing a stress management layer on the carbon-containing layer. The stress management layer has a tensile stress. Thus, the overall stress in a structure comprising a stress management layer overlying a carbon-containing layer may be reduced. Accordingly, the present methods allow for improved stress management in a patterning stacks. This in turn results in lower line edge roughness (LER) and/or line width roughness (LWR) after etch.

It shall be understood that the term “stress” as used herein may refer to film stress or intrinsic stress of the relevant layers.

In some embodiments, the carbon-containing layer consists essentially of carbon. In some embodiments, the carbon-containing layer comprises carbon and hydrogen. The carbon-containing layer may consist primarily of sp2 and sp3 carbon, e.g., the carbon-containing layer may comprise more than 50 atomic percent, more than 60 atomic percent, more than 70 atomic percent, more than 80 atomic percent, more than 90 atomic percent, or more than 95 atomic percent of combined sp2 and sp3 carbon. In some embodiments, the carbon-containing layer comprises 1.0 to 50.0 atomic percent hydrogen, or 1.0 to 10.0 atomic percent hydrogen, or 10.0 to 20.0 atomic percent hydrogen, or 20.0 to 30.0 atomic percent hydrogen, or 30.0 to 40.0 atomic percent hydrogen, or 40.0 to 50.0 atomic percent hydrogen.

In some embodiments, the carbon-containing layer comprises one or more elements selected from the list consisting of N, P, B, S, CI, I, Br, F, and O.

In some embodiments, the carbon-containing layer has a thickness of 20 nm to 500 nm, or of 50 nm to 400 nm, or of 100 nm to 250 nm, or of 150 nm to 200.

The stress management layer may be deposited by means of a plasma enhanced-deposition process. In other words, the step of providing the precursor to the reaction chamber to deposit the layer may comprise the provision of a plasma, e.g., a direct plasma provided in the reaction chamber or a remote plasma for providing radicals to the reaction chamber. Additionally or alternatively, the stress management layer may be deposited by means of a cyclical deposition process. Thus, in some embodiments, the stress management layer is deposited by means of a plasma-enhanced cyclical deposition process, such as a plasma-enhanced atomic layer deposition process, or a plasma-enhanced cyclic chemical vapor deposition process.

In some embodiments, the cyclical deposition process comprises cyclically providing precursor pulses and reactant pulses to the reaction chamber. The precursor pulses comprise providing the precursor to the reaction chamber. The reactant pulses comprise providing the reactant to the reaction chamber. In some embodiments, the precursor pulses and the reactant pulses are separated by purges, e.g., by providing a noble gas to the reaction chamber in between a precursor pulse and a reactant pulse. In some embodiments, the cyclical deposition process comprises exposing the substrate to a plasma. The plasma may either be continuous or pulsed.

In some embodiments, the stress management layer is further subjected to a plasma treatment after it has been deposited. For example, the stress management layer may be subjected to a plasma, e.g., a hydrogen plasma, a nitrogen plasma, or a noble gas plasma. An exemplary noble gas plasma includes an argon plasma. The plasma treatment may employ a remote plasma, e.g. a remote hydrogen plasma, such that the stress management layer can be treated with hydrogen radicals. Alternatively, the plasma treatment may employ a direct plasma such as an argon plasma, such that the stress management layer may be treated with a broader variety of reactive species such as ions and radicals. The plasma treatments may advantageously be used to control the tensile stress in the stress management layer and/or to tune the surface chemistry of the stress management layer, e.g., to improve adhesion between the stress management layer and an underlayer that may be deposited on top of the stress management layer.

In some embodiments, the method further comprises depositing an underlayer on the stress management layer. Suitably, the underlayer has a thickness of less than 5 nm.

In some embodiments, the underlayer has a surface energy having a polar part and a dispersive part, wherein polar part of the surface energy is from at least 3 mN/m to at most 13 mN/m. Thus the underlayer may offer suitable adhesion to a resist, e.g., a positive tone EUV (extreme ultraviolet) resist or a negative tone EUV resist. Note that an EUV resist indicates a resist which is sensitive to extreme ultraviolet radiation.

In some embodiments, the underlayer comprises silicon, oxygen, hydrogen, and carbon. In some embodiments, the underlayer further comprises nitrogen.

In some embodiments, the underlayer comprises a bi-layer structure comprises an upper underlayer part and a lower underlayer part. The lower underlayer part comprises a metal or metalloid. Advantageously, the upper underlayer part comprises a dielectric comprising silicon, carbon, and oxygen. In other words, the upper underlayer part may comprise an SiOC layer.

The underlayer may, for example, be deposited on the stress management layer by means of a plasma-enhanced deposition technique such as plasma-enhanced chemical vapor deposition, cyclical plasma-enhanced chemical vapor deposition, and plasma-enhanced atomic layer deposition. Alternatively, the underlayer may be deposited on the stress management layer by means of a thermal technique such as thermal chemical vapor deposition and thermal atomic layer deposition.

After the underlayer has been formed, it may be additionally exposed to a plasma. The plasma suitably comprises one or more elements selected from the list consisting of a halogen, oxygen, hydrogen, and nitrogen. A suitable halogen includes chlorine. The plasma may be used for tuning the surface energy of the underlayer.

In some embodiments, the stress management layer is deposited using a precursor containing carbon and hydrogen. In some embodiments, the stress management layer is deposited using a reactant selected from the list consisting of O₂, CO₂, N₂O, CO, a mixture of N₂ and a noble gas, a mixture of N₂ and H₂, and a mixture of NH₃ and a noble gas. In some embodiments, the noble gas may be selected from Ar and He. In exemplary embodiments, one of these reactants may be used together with a precursor comprising carbon and hydrogen in order to deposit a stress management layer.

In some embodiments, the ratio of the carbon concentration and the hydrogen concentration in the stress management layer is at least 0.8, when the carbon concentration and the hydrogen concentration are expressed on a per mol basis. Such a high carbon to hydrogen concentration ratio may provide various advantages such as denser films, increased stability, increased stress control, easier process control during deposition, and faster deposition.

In some embodiments, the precursor further comprises a halogen. In some embodiments, the halogen comprises bromine. In other words, in some embodiments, the precursor is an organobromine precursor. In some embodiments, the precursor comprises tribromomethane.

In some embodiments, the precursor comprises fluorine. In some embodiments, the precursor consists of a fluorocarbon. In some embodiments, the precursor comprises C₈F₁₈. One advantage related to the use of C₈F₁₈ is that it is a liquid precursor, and may be particularly easy to handle.

In some embodiments, the precursor further comprises oxygen and/or nitrogen.

In some embodiments, the precursor further comprises phosphorous and/or boron.

In some embodiments, the precursor comprises a C₁ to C₂₀ alkane, a C₁ to C₂₀ alkene, a C₁ to C₂₀ alkyl, or a C₁ to C₂₀ polyunsaturated hydrocarbon. In some embodiments, the precursor comprises CH₄. Such hydrocarbon precursors may be particularly easy to handle. In addition, they tend to have low chemisorption.

In some embodiments, the precursor comprises an aromatic compound. In some embodiments, the precursor is selected from toluene and trimethylbenzene.

In some embodiments, the precursor is an aliphatic compound.

In some embodiments, the stress management layer is deposited by means of trimethylboron, triethylboron, or tripropylboron as a precursor and a noble gas as a reactant. For example, the noble gas may consist of argon.

In some embodiments, the stress management layer is volatilizable by means of an oxygen plasma or a nitrogen plasma. Thus, the stress management layer may be removed together with the carbon-containing layer, e.g., after an etch. This can be done, for example, by means of an organic stress management layer which is deposited according to the methods which are described herein, and using the precursors and reactants mentioned herein. Advantageously, such a stress management layer does not substantially comprise hard to volatilize atoms such as silicon, titanium, or zinc. These elements form respectively oxides or nitrides when exposed to an oxygen or nitrogen plasma, which are solids with very low vapor pressure at common operating conditions, and may therefore be undesirable in the present stress management layers.

In some embodiments, the precursor can include at least one silicon-R bond, wherein R is selected from one or more of the group consisting of alkyl, alkenyl, alkynyl, aryl, alkoxy, halogen, and hydrogen. In some cases, the at least one organic group comprises at least two organic groups.

In some embodiments, the stress management layer is deposited at a temperature of at least 20° C. to at most 400° C., or from at least 100° C. to at most 300° C., or from at least 150° C. to at most 250° C.

In some embodiments, the stress management layer is deposited at a pressure of at least 1.0 Torr to at most 50.0 Torr, or from at least 2.0 Torr to at most 25.0 Torr, or from at least 5.0 Torr to at most 15.0 Torr, or 10.0 Torr.

Further described is a system comprising one or more reaction chambers. The system is configured for carrying out a method as described herein.

Further described is a method for forming a structure. The method comprises providing a substrate and forming a carbon-containing layer overlying a surface of the substrate. The carbon-containing layer thus formed has a compressive stress. Then, a stress management layer is formed overlying the carbon-containing layer. This stress management layer has a tensile stress. The stress management layer suitably compensates for at least some of the compressive stress in the carbon-containing layer. The stress management layer can be suitably formed using the methods, precursors, and reactants described herein. Next, an underlayer is deposited on the stress management layer. The underlayer, and/or its surface, may or may not be subjected to a plasma treatment after the underlayer has been deposited. After the underlayer has been formed, a photoresist layer overlying the underlayer is deposited. The photoresist layer comprises extreme ultraviolet (EUV) lithography photoresist. The thusly formed structures allow the definitions of very small lithographic patterns with minimal roughness.

Turning now to the figures, FIG. 1 illustrates a structure (100) in accordance with exemplary embodiments of the disclosure. The structure (100) includes a substrate (102), a patternable layer (104), a carbon-containing layer (106), a stress management layer (108), an underlayer (110), and a positive tone EUV photoresist layer (112).

The substrate (102) can include a substrate as described above. By way of example, the substrate (102) can include a semiconductor substrate, such as a bulk material, such as silicon (e.g., single-crystal silicon), other Group IV semiconductor material, Group III-V semiconductor material, and/or Group II-VI semiconductor material and can include one or more layers overlying the bulk material. Further, as noted above, the substrate can include various topologies, such as recesses, lines, and the like formed within or on at least a portion of a layer of the substrate.

The patternable layer (104) is optional, and is a layer in which a pattern may be lithographically applied. When included, the material layer (104) can include, for example, an oxide, such as a native oxide, amorphous carbon, or a field oxide. Other exemplary layers include nitrides, other oxides, silicon, and add-on films (e.g. a self-assembled monolayer (e.g., hexamethyldisilazane (HMDS)). It shall be understood that, when the patternable layer (104) is not present, a lithographical pattern may be etched in, or applied on, the substrate.

The carbon-containing layer (106) may comprise, for example, sp3 carbon, sp2 carbon, and/or diamond-like carbon. In some embodiments, the carbon-containing layer may further comprise halides, B, P, S, C, N, and/or O. The carbon-containing layer (106) has a compressive stress, and may serve as a hardmask for patterning. The compressive stress of the carbon-containing layer (106) may cause undesirable wafer bowing and/or may induce increased line roughness of lithographically defined patterns.

The stress management layer (108) may be deposited using methods as described herein, and comprises carbon and hydrogen. Additionally, the stress management layer (108) may comprise oxygen, nitrogen, and/or one or more halogens. Preferably the stress management layer (108) does not comprise elements such as silicon, titanium, and zinc, which may form non-volatile compounds when the stress-management layer is removed after patterning using, for example, an oxygen or nitrogen plasma. In some embodiments, the stress management layer consists of C, H, O, and N. The thickness of the stress management layer (108) may be, for example, from at least 1.0 nm to at most 25.0 nm, or from at least 2.0 nm to at most 20 nm, or from at least 5.0 nm to at most 15.0 nm, or at most 10.0 nm. The stress management layer (108) has a tensile stress and can at least partially compensate for the compressive stress in the carbon-containing layer.

The thickness of the underlayer can depend on the thickness of the patternable layer (104), or the thickness of the substrate (102)) to be etched, the thickness of the carbon-containing layer (106), the thickness of the stress-management layer (108), a type of photoresist, and the like. In accordance with examples of the disclosure, the underlayer (110) has a thickness of less than 10 nm or less than or about 5 nm. In some embodiments, the underlayer (110) has a thickness of from at least 1.0 nm to at most 2.0 nm, or from at least 2.0 nm to at most 5.0 nm, or from at least 5.0 nm to at most 10.0 nm. If the underlayer (110) is too thick, a residual underlayer material may remain after an etch step, described in connection with FIGS. 4 and 5. A surface of the underlayer (110) may or may not be treated with a plasma treatment, to provide desired surface terminations to, for example, promote adhesion with the photoresist layer (112). Alternatively, and in some embodiments, the plasma treatment may be used to reduce adhesion with a photoresist layer (112), since excessive adhesion tends to be undesirable since it may cause resist residuals remaining on the substrate in exposed areas, an effect called scumming.

In some embodiments, the underlayer comprises a material selected from the list consisting of amorphous carbon, a chlorosilanes such as octadecyltrichlorosilane and alkoxysilanes such as dimethyldimethoxysilane.

In accordance with examples of the disclosure, the underlayer (110) comprises SiOC. As used herein, unless stated otherwise, SiOC is not intended to limit, restrict, or define the bonding or chemical state, for example, the oxidation state of any of Si, O, C, and/or any other element in the film. Further, in some embodiments, SiOC thin films may comprise one or more elements in addition to Si, O, and/or C, such as H or N. In some embodiments, the SiOC films may comprise Si—C bonds and/or Si—O bonds. In some embodiments, the SiOC films may comprise Si—C bonds and Si—O bonds and may not comprise Si—N bonds. In some embodiments, the SiOC films may comprise Si—H bonds in addition to Si—C and/or Si—O bonds. In some embodiments, the SiOC films may comprise more Si—O bonds than Si—C bonds, for example, a ratio of Si—O bonds to Si—C bonds may be from about 1:10 to about 10:1. In some embodiments, the SiOC may comprise from about 0% to about 50% carbon on an atomic basis. In some embodiments, the SiOC may comprise from about 0.1% to about 40%, from about 0.5% to about 30%, from about 1% to about 30%, or from about 5% to about 20% carbon on an atomic basis. In some embodiments, the SiOC films may comprise from about 0% to about 70% oxygen on an atomic basis. In some embodiments, the SiOC may comprise from about 10% to about 70%, from about 15% to about 50%, or from about 20% to about 40% oxygen on an atomic basis. In some embodiments, the SiOC films may comprise about 0% to about 50% silicon on an atomic basis. In some embodiments, the SiOC may comprise from about 10% to about 50%, from about 15% to about 40%, or from about 20% to about 35% silicon on an atomic basis. In some embodiments, the SiOC may comprise from about 0.1% to about 40%, from about 0.5% to about 30%, from about 1% to about 30%, or from about 5% to about 20% hydrogen on an atomic basis. In some embodiments, the SiOC films may not comprise nitrogen. In some other embodiments, the SiOC films may comprise from about 0% to about 40% nitrogen on an atomic basis (at %). By way of particular examples, SiOC films can be or include a layer comprising SiOCH, such as SiOCNH. Advantageously, the SiOC films may be non-porous.

The underlayer may be deposited, for example, using a plasma-assisted cyclic deposition process, such as plasma-assisted atomic layer deposition or chemical vapor deposition, for example by means of the methods described in U.S. patent application Ser. No. 16/922,520, which is hereby incorporated by reference in its entirety.

The underlayer (110) desirably exhibits good adhesion and other properties as described herein. To provide desired adhesion between the photoresist layer (112) and the underlayer (110), the underlayer (110) may have or be tuned to have desired surface chemistry properties, e.g., quantified as surface energy, which is further categorized into a polar part of surface energy and a disperse part of surface energy. The polar part of surface energy and the disperse part of surface energy of photoresist underlayer (110) can be calculated by measuring a contact angle of a liquid, such as water or CH₂l₂, and using the Owens, Wendt, Rabel and Kaelble (OWRK) method to determine the polar part and the disperse part of the surface energy. The same properties can be measured and calculated for the photoresist layer (112).

In some cases, for positive tone photoresist, the polar part of surface energy of the underlayer (110) can be between about 0 to about 15 mN/m. In accordance with further examples, the polar part of surface energy of the underlayer (110) is within about −100% to about +60% of a value of a polar part of surface energy of the photoresist. The disperse part of the photoresist underlayer can be in the range of 20-35 mN/m.

FIG. 2 illustrates a structure (200), which can be formed by providing a mask overlying a structure (100) and exposing the masked structure to extreme ultraviolet light (e.g., light having wavelengths between about 13.3 and 13.7 nm) to form exposed structures (202) and unexposed structures (204).

FIG. 3 illustrates a structure (300) after a development process to remove exposed structures (202). After the removal of the structures (202), an etch process can be performed to remove sections of the patternable layer (104), the carbon-containing layer (106), the stress management layer (108), and the underlayer (110) to form structures (400, 500) as illustrated in FIGS. 4 and 5.

The structure (400) shown in FIG. 4 includes features (402), which can include photoresist material (section 412), and underlayer material (410). The structure (500) shown in FIG. 5 includes features (501) that include patternable material (504), carbon-containing material (506), stress management material (508), and underlayer material (510), and, in some cases, photoresist material. FIG. 6 illustrates a structure (600), including structures (602) after the carbon-containing layer, the stress management layer, the underlayer, and optionally the photoresist are removed from the structure (500) shown in FIG. 5.

The photoresist layer (112) can be or include any suitable positive tone EUV photoresist material, such as chemically amplified resist (CAR). By way of examples, the photoresist layer (112) is or includes Poly(4-hydroxystyrene) (PHS), styrene derivatives and acrylate copolymers. Photoacid generator (e.g. triphenylsulfonium triflate) and base quencher (amines or conjugated bases) might also be present in the photoresist layer (112).

FIGS. 7-12 illustrate similar structures for negative tone photoresist. FIG. 7 illustrates a structure (700) that includes a substrate (702), a patternable layer (704), a carbon-containing layer (706), a stress management layer (708), an underlayer (710), and a negative tone EUV photoresist layer (712). The substrate (702) and the patternable layer (704) can be the same or similar to the substrate (102) and the patternable layer (104) described above in connection with FIGS. 1 to 6.

The thickness of the underlayer (710) can depend on the thickness of the patternable layer (704) which is to be etched, the type of photoresist used, and the like. In accordance with examples of the disclosure, the underlayer (710) may have a thickness of less than 10 nm, or less than 5 nm, e.g. from at least 1.0 nm to at most 5.0 nm.

The underlayer 710 can be formed of the same or similar materials described above in connection with the underlayer (110) described in the context of FIGS. 1 to 6. The surface of photoresist underlayer 710 may desirably be treated with a plasma treatment, as described below, to provide desired surface terminations to promote adhesion with the negative tone photoresist layer (712). Alternatively, and in some embodiments, a plasma treatment may be used to reduce adhesion with a negative tone photoresist layer. In accordance with examples of the disclosure, the photoresist underlayer (710) includes a surface comprising —CH_(x), Si—H and/or OH terminated groups, the ratio of the groups can be fine-tuned to achieve desired surface chemistry properties or pattern profile with the target photoresist.

The underlayer (710) also desirably exhibits desired adhesion and other properties as described herein. To provide desired adhesion between the photoresist layer (712) and the photoresist underlayer (710), the photoresist underlayer (710) may have or be tuned to have desired surface energy properties, i.e., a polar part of surface energy and a disperse part of surface energy. The polar part of surface energy and the disperse part of surface energy of photoresist underlayer (710) can be calculated by measuring a contact angle of a liquid, such as water or CH₂l₂, and using the Owens, Wendt, Rabel and Kaelble (OWRK) method to determine the polar part and the disperse part of the surface energy. The same properties can be measured and calculated for the photoresist layer (712). In accordance with various examples of the disclosure, the polar part of surface energy of the underlayer (710) is within about −20% to about +20% or about −10% to about +10% percent of a value of the respective polar part of surface energy of the photoresist layer (712). The disperse part of the photoresist underlayer can be, for example, in the range of 20-35 mN/m.

The photoresist layer (712) can be or include any suitable negative tone EUV photoresist (e.g., CAR) material. By way of examples, the photoresist layer (712) is or includes poly(4-hydroxystyrene) (PHS), styrene derivatives and acrylate copolymers. Photoacid generator (e.g. triphenylsulfonium triflate) and base quencher (amines or conjugated bases) might also be present in the photoresist layer (712).

FIGS. 8-12 illustrate similar steps illustrated in FIGS. 2-6, except a negative tone photoresist layer (712) is used rather than a positive tone photoresist (112). FIG. 8 illustrates a structure (800), which can be formed by providing a mask overlying structure 700 and exposing the masked structure to EUV to form exposed structures (802) and unexposed structures (804).

FIG. 9 illustrates a structure (900) after a development process to remove unexposed structures (804). After the removal of these structures (804), an etch process can be performed to remove sections of the underlayer (710), the stress management layer (708), the carbon-containing layer (706), and the patternable layer (704) to form structures 1000 and 1100, illustrated in FIGS. 10 and 11.

The structure (1000) shown in FIG. 10 includes features (1001), which can include photoresist material (1004) and underlayer material (1006). The structure (1100) shown in FIG. 11 includes features (1101) that include patternable layer material (1104), carbon-containing layer material (1106), stress management layer material (1108), underlayer material (1110), and optionally photoresist material.

FIG. 12 illustrates a structure (1200), including structures (1202) after the carbon-containing layer, the stress management layer, and optionally the photoresist have been removed from the structure (1100) shown in FIG. 11.

Turning now to FIG. 13, a method (1300) of forming a structure in accordance with at least one embodiment of the disclosure is illustrated. The method (1300) includes the steps of providing a substrate (1301), forming a carbon-containing layer (1302), forming a stress management layer (1303), forming an underlayer (step 1304), a treatment (step 1306), and forming a layer of photoresist (step 1308). In some cases, the treatment step (1306) can be optional.

Step 1301 can include providing a substrate, such as a substrate described herein. The substrate can include a layer, such as a patternable layer described above for pattern transfer. By way of examples, the substrate can include a deposited oxide, a native oxide, or an amorphous carbon layer.

The carbon-containing layer may be deposited using techniques which are known as such, including methods based on PEALD or PECVD. The carbon-containing layer has compressive stress, which may result in problems related to wafer bowing and/or pattern roughness.

The stress management layer may be suitably deposited using the methods and techniques described herein. Plasma-enhanced processes such as PEALD and PECVD may be especially suitable. In some cases, PEALD may be preferred over PECVD, because PEALD can allow for better uniformity and control of thickness. This, in turn, can lead to decreased roughness which can be important for, for example, stress management layers having a thickness of 10 nm or less, or 5 nm or less. Stress management layers having a thickness of 10 nm or less, or 5 nm or less, may be desirable, for example, because of compatibility with low etch budgets. And, PEALD processes may be performed at lower temperatures—compared to similar PECVD processes. The step (1303) of forming the stress management layer can be performed in a reactor, e.g., in a reactor commercially available from ASM International NV (Almere, The Netherlands).

During the step of forming the underlayer (1304), the underlayer can be formed using a plasma-enhanced cyclic deposition process, such as plasma-enhanced atomic layer deposition (PEALD), and plasma-enhanced chemical vapor deposition (PECVD). The underlayer (1304) can be advantageously formed by means of the methods described in U.S. patent application Ser. No. 16/922,520.

A treatment step (1306) can be used to tune a surface of an underlayer to modify a surface of the photoresist underlayer. In particular, the disperse and/or polar parts of the underlayer's surface energy may be altered by means of the techniques described in U.S. patent application Ser. No. 16/922,520. The treatment step (1306) may be particularly desirable for use with negative tone EUV photoresist layers.

As shown in FIG. 14, an underlayer (1420) as described herein may comprise a bi-layer structure comprising an upper underlayer part (1422) and a lower underlayer part (1421) and a photoresist layer (1423) overlying underlayer (1420). The underlayer is positioned on top of a stress management layer (1415), which in turn is positioned on a carbon-containing layer (1411). The lower underlayer part (1421) may comprise a metal or metalloid. The upper underlayer part (1422) may be used for example, as an adhesion layer and/or as a developer blocking layer, i.e. as a layer that protects underlying layers against developer. Thus, the underlayer of FIG. 14 offers simultaneous good adhesion and etch resistance by employing an etch resistant lower underlayer part (1421) and an adhering and developer-blocking upper underlayer part (1422). An underlayer (1420) having such a structure may be deposited using the methods described in U.S. patent application Ser. No. 16/922,520. The stress management layer (1415) and/or the carbon-containing layer (1411) may be deposited in the same reactor chamber as the lower underlayer part (1421) and/or the upper underlayer part (1422). The different reactor chambers may be comprised in a single cluster tool, the cluster tool comprising two or more reactor chambers and a wafer transfer module arranged for transporting substrates from one reactor chamber to another.

An exemplary cyclical deposition process for forming a stress management layer is illustrated in FIG. 15. In particular, FIG. 15 shows plasma power (1501) always on, and a continuous plasma gas, i.e. reactant gas, flow (1502). Precursor flow (1503) is provided in pulses. Optionally, the precursor pulses are separated by purges (not shown). A timeline (1504) indicates the flow of time from left to right.

Another exemplary cyclical deposition process for forming a stress management layer is illustrated in FIG. 16. In particular, FIG. 16 shows a continuous flow (1602) of plasma gas, i.e., reactant gas. In addition, the plasma power (1601) is pulsed. Precursor flow (1603) is provided in pulses as well. Optionally, the precursor pulses are separated by purges (not shown). A timeline (1604) indicates the flow of time from left to right.

The example embodiments of the disclosure described above do not limit the scope of the invention, since these embodiments are merely examples of the embodiments of the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the disclosure, in addition to the embodiments shown and described herein, such as alternative useful combinations of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims. 

What is claimed is:
 1. A method for forming a structure comprising: providing a substrate comprising a carbon-containing layer having a compressive stress to a reaction chamber; providing a precursor in the reaction chamber to deposit a stress management layer on the carbon-containing layer; wherein the stress management layer has a tensile stress.
 2. The method according to claim 1 wherein providing a precursor in the reaction chamber to depositing a stress management layer comprises providing a plasma in the reaction chamber.
 3. The method according to claim 1 wherein the precursor comprises carbon and hydrogen.
 4. The method according to claim 3 wherein the ratio of the carbon concentration and the hydrogen concentration in the stress management layer is at least 0.8, when the carbon concentration and the hydrogen concentration are expressed on a per mol basis.
 5. The method according to claim 3 wherein the precursor further comprises a halogen.
 6. The method according to claim 3 wherein the precursor further comprises oxygen and/or nitrogen.
 7. The method according claim 3 wherein the precursor further comprises phosphorous and/or boron.
 8. The method according to claim 1 wherein the stress management layer is deposited using a reactant selected from the list consisting of O₂, CO₂, N₂O, CO, a mixture of N₂ and a noble gas, a mixture of N₂ and H₂, and a mixture of NH₃ and a noble gas.
 9. The method according to claim 8 wherein the precursor comprises triethylboron and the reactant comprises Ar.
 10. The method according to claim 8 wherein the stress management layer is deposited using a cyclical deposition process, the cyclical deposition process comprising cyclically providing precursor pulses and reactant pulses to the reaction chamber, wherein the precursor pulses comprise providing the precursor to the reaction chamber, and wherein the reactant pulses comprise providing the reactant to the reaction chamber.
 11. The method according to claim 10 wherein the cyclical deposition process further comprises exposing the substrate to a plasma.
 12. The method according to claim 1 wherein the stress management layer does not comprise silicon, titanium, or zinc.
 13. The method according to claim 12 wherein the stress management layer consists of C, H, O, and N.
 14. The method according to claim 1 further comprising a step of depositing an underlayer on the stress management layer.
 15. The method according to claim 14 wherein the underlayer has a thickness of less than 5 nm.
 16. The method according to claim 14 wherein the underlayer has a surface energy having a polar part and a dispersive part, wherein polar part of the surface energy is from at least 3 mN/m to at most 13 mN/m.
 17. The method according to claim 14 wherein the underlayer comprises silicon, oxygen, hydrogen, and carbon.
 18. The method according to claim 14 wherein the underlayer comprises a bi-layer structure comprising an upper underlayer part and a lower underlayer part, wherein the lower underlayer part comprises a metal or metalloid.
 19. A system comprising one or more reaction chambers configured for carrying out a method according to claim
 1. 20. A method of forming a structure, the method comprising the steps of: providing a substrate; forming a carbon-containing layer overlying a surface of the substrate, the carbon-containing layer having a compressive stress; forming a stress management layer overlying a surface of the carbon-containing layer, the stress management layer having a tensile stress; forming an underlayer overlying a surface of the stress management layer; and forming a photoresist layer overlying the underlayer, the photoresist layer comprising extreme ultraviolet (EUV) lithography photoresist. 